+++ /dev/null
-#include <linux/module.h>
-#include <linux/gpio.h>
-#include <linux/hrtimer.h>
-#include <linux/interrupt.h>
-#include <linux/ktime.h>
-#include <linux/proc_fs.h>
-#include <linux/seq_file.h>
-#include <linux/version.h>
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Nuno Goncalves");
-MODULE_DESCRIPTION("GL-MiFi power monitoring MCU interface");
-MODULE_VERSION("0.1");
-
-static int gpio_tx = 19;
-static int gpio_rx = 8;
-static int baudrate = 1200;
-static int query_interval_sec = 4;
-
-static struct hrtimer timer_tx;
-static struct hrtimer timer_rx;
-static ktime_t period;
-static int rx_bit_index = -1;
-
-static unsigned read_buf_ready = 0;
-static unsigned read_buf_size = 0;
-static char read_buf[2][64] = {{0},{0}};
-
-static int proc_show(struct seq_file *m, void *v)
-{
- seq_printf(m, "%s\n", read_buf[read_buf_ready]);
- return 0;
-}
-
-static int proc_open(struct inode *inode, struct file *file)
-{
- return single_open(file, proc_show, NULL);
-}
-
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)
-static const struct proc_ops hello_proc_ops = {
- .proc_open = proc_open,
- .proc_read = seq_read,
- .proc_lseek = seq_lseek,
- .proc_release = single_release,
-};
-#else
-static const struct file_operations hello_proc_ops = {
- .owner = THIS_MODULE,
- .open = proc_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
-};
-#endif
-
-static irqreturn_t handle_rx_start(int irq, void* device)
-{
- if (rx_bit_index == -1)
- {
- hrtimer_start(&timer_rx, ktime_set(0, period / 2), HRTIMER_MODE_REL);
- }
- return IRQ_HANDLED;
-}
-
-static enum hrtimer_restart handle_tx(struct hrtimer* timer)
-{
- ktime_t current_time = ktime_get();
- const unsigned char character = 'g';
- static int bit_index = -1;
-
- // Start bit.
- if (bit_index == -1)
- {
- gpio_set_value(gpio_tx, 0);
- bit_index++;
- }
-
- // Data bits.
- else if (0 <= bit_index && bit_index < 8)
- {
- gpio_set_value(gpio_tx, 1 & (character >> bit_index));
- bit_index++;
- }
-
- // Stop bit.
- else if (bit_index == 8)
- {
- gpio_set_value(gpio_tx, 1);
- bit_index = -1;
- }
-
- hrtimer_forward(&timer_tx, current_time, bit_index == 8
- ? ktime_set(query_interval_sec, 0) //wait for next query cycle
- : period); //wait for next bit period
-
- return HRTIMER_RESTART;
-}
-
-void receive_character(unsigned char character)
-{
- if(character == '{')
- read_buf_size = 0;
-
- if(read_buf_size < (sizeof(read_buf[0])-1) || character == '}')
- {
- read_buf[!read_buf_ready][read_buf_size++] = character;
- if(character == '}')
- {
- read_buf[!read_buf_ready][read_buf_size] = '\0';
- read_buf_ready = !read_buf_ready;
- read_buf_size = 0;
- }
- }
-}
-
-static enum hrtimer_restart handle_rx(struct hrtimer* timer)
-{
- ktime_t current_time = ktime_get();
- static unsigned int character = 0;
- int bit_value = gpio_get_value(gpio_rx);
- enum hrtimer_restart result = HRTIMER_NORESTART;
- bool must_restart_timer = false;
-
- // Start bit.
- if (rx_bit_index == -1)
- {
- rx_bit_index++;
- character = 0;
- must_restart_timer = true;
- }
-
- // Data bits.
- else if (0 <= rx_bit_index && rx_bit_index < 8)
- {
- if (bit_value == 0)
- {
- character &= 0xfeff;
- }
- else
- {
- character |= 0x0100;
- }
-
- rx_bit_index++;
- character >>= 1;
- must_restart_timer = true;
- }
-
- // Stop bit.
- else if (rx_bit_index == 8)
- {
- receive_character(character);
- rx_bit_index = -1;
- }
-
- // Restarts the RX timer.
- if (must_restart_timer)
- {
- hrtimer_forward(&timer_rx, current_time, period);
- result = HRTIMER_RESTART;
- }
-
- return result;
-}
-
-static int __init gl_mifi_mcu_init(void)
-{
- bool success = true;
-
- proc_create("gl_mifi_mcu", 0, NULL, &hello_proc_ops);
-
- success &= gpio_request(gpio_tx, "soft_uart_tx") == 0;
- success &= gpio_direction_output(gpio_tx, 1) == 0;
- success &= gpio_request(gpio_rx, "soft_uart_rx") == 0;
- success &= gpio_direction_input(gpio_rx) == 0;
- success &= gpio_set_debounce(gpio_rx, 1000/baudrate/2);
-
- success &= request_irq(
- gpio_to_irq(gpio_rx),
- handle_rx_start,
- IRQF_TRIGGER_FALLING,
- "gl_mifi_mcu_irq_handler",
- NULL) == 0;
-
- hrtimer_init(&timer_tx, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
- timer_tx.function = &handle_tx;
- hrtimer_init(&timer_rx, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
- timer_rx.function = &handle_rx;
- period = ktime_set(0, 1000000000/baudrate);
- hrtimer_start(&timer_tx, period, HRTIMER_MODE_REL);
-
- return success;
-}
-
-static void __exit gl_mifi_mcu_exit(void)
-{
- disable_irq(gpio_to_irq(gpio_rx));
- hrtimer_cancel(&timer_tx);
- hrtimer_cancel(&timer_rx);
- free_irq(gpio_to_irq(gpio_rx), NULL);
- gpio_set_value(gpio_tx, 0);
- gpio_free(gpio_tx);
- gpio_free(gpio_rx);
- remove_proc_entry("gl_mifi_mcu", NULL);
-}
-
-module_init(gl_mifi_mcu_init);
-module_exit(gl_mifi_mcu_exit);
-